De'Vion Harmon scored 22 points to lead Oklahoma to a 75-68 win over No. 9 Kansas on Saturday in Norman, Okla.
The Jayhawks (10-5, 4-4 Big 12) have dropped three consecutive games for the first time since 2013.
The Sooners (9-4, 5-3) improved to 8-1 at home and have won three consecutive games.
Both teams' leading scorers, Oklahoma's Austin Reaves and Kansas' Ochai Agbaji, were held scoreless in the first half.
Reaves and Agbaji each came on strong after the break, with Reaves' aggressiveness helping make the difference.
The Sooners didn't attempt a free throw in the first half but made 18 of 22 in the second half, with Reaves scoring 10 of his 16 points from the line.
Agbaji scored 10 second-half points while Marcus Garrett led Kansas with 21 points and 12 rebounds.
Harmon outdueled his former high school teammate, Jalen Wilson. Wilson finished with 13 points of 5-of-7 shooting for the Jayhawks.
The Sooners led for the final 8:57. Reaves contributed a jumper and a three-point play on consecutive possessions to put Oklahoma ahead 63-56 with 5:12 to play.
Agbaji's 3-pointer pulled Kansas within 67-63 with 1:55 remaining, but Reaves and Elijah Harkless each made a pair of free throws to push the lead back to eight with 49 seconds left.
Kansas shot 46.3 percent overall and 36.4 percent (8 of 22) from 3-point range. Oklahoma won the battle of the boards 36-25 and shot 45.3 percent from the field and 37.5 percent (9 of 24) from downtown.
The Sooners led 29-28 at halftime despite missing 10 of their last 12 field-goal attempts before the break. Oklahoma was scoreless for the last four minutes of the half.
Kansas led 16-10 early before the Sooners ripped off a 14-0 run to take their largest lead at 24-16 on a 3-pointer by Umoja Gibson.
--Field Level Media